Thermal pump



Nov. 13, 1945. E. M. LIEBERMAN THERMAL PUMP Filed Nov. 13, 1943 2Sheets-Sheet 1 INVENTOR: Y

AGENT Nov. 13, 1945. l-:.M.l LIEBERMAN THERMAL PUMP Filed NOV. 13, 19432 Sheets-Sheefl 2 AGENT Patented Nov. 13, 1945 UNITED STATESv PATENTgoFFlcE THERMAL PUMP Edgar M. Lieberman, Kansas City, Mo.

Application November 13, 1943, Serial No. 510,148

15 Claims.

This invention relates to pumps and more particularly to a thermal pumpemploying steam or liquid vapor as the motive force for use in elevatingor circulating liquids, and has for its principal object to provide apumping apparatus in which steam or the like is generated and employedto provide motive energy for a reciprocating pump piston.

Other objects of the invention are to provide a combinationreciprocating pump and ash type boiler for generating steam in theboiler for reciprocating a pump plunger; to provide a supply of liquidto the boiler in response to reciprocation of the pump plunger; toprovide for metering the liquid supply to the boiler; to provide forexhausting the steam from the pump cylinder and boiler to reducepressure therein; to provide for delivering the exhausted steam from thecylinder and boiler to the liquid intake duct; to provide a steam jetfrom the pump cylinder for expediting flow through the liquid inletduct; to provide for condensing the steam in the boiler'by fresh liquidsupply to eiect reduction in pressure therein for accelerating thereturn stroke of the pump piston; to provide a resilient member forexpediting the return stroke of the piston; to provide a pump havingautomatic means for controlling the pumping operation; to providecontrol of the pump operation responsive to control of the boilerheating flame; and to provide improved elements and arrangements thereofin a thermal pump of the character and for the purpose noted.

In accomplishing these and other objects in the present invention, Ihave provided improved vdetails of structure, the preferred form of,which is illustrated in the accompanying drawings wherell'lI Fig. 1 isa detail vertical section through a thermal pump embodying the featuresof the present invention.

Fig. 2 is a detail vertical section showing a modified arrangement ofthe pump exhaust passage for delivering the jet to the liquid intakeduct.

Fig. 3 is a detail vertical section showing a further modifiedarrangement of the liquid metering device and boiler for operation ofthe pump.

Referring more in detail to the drawings:

l designates a pump body which may be formed of metal, plastic or othersuitable material and preferably contains all of the operating elementsof the apparatus and ow channels therefor.. The body preferably consistsof a single block of material provided with a bore 2 adjacent one sidethereof and formed from the bottom 3 of the body. The bore forms acylinder for a reciprocable piston 4 of suitable size to closely nt thewalls of the bore 2, said piston being inserted from the bottom of thebody and the bore closed by means of a thin metal plug 5 having externalthreads 6 adapted to engage internal threads 'l in the body for securingsaid plug therein. The upper end of the bore 2 terminates short of thetop 8 of the body as at 9 and is provided with a passage I0 of smallersize than the bore 2 to provide a shoulder I I at the upper end of thebore for a purpose later described. The passage Ill communicates thebore 2 with a head chamber I2 spaced upwardly from the end 9 of the bore2 and formed by a transverse bore opening from the side I3 of the bodyand extending through said body to a point approximately midway betweenthe bore 2 and the side I4 of said pump body, the open-end of thechamber I2 being closed by a plug I5 having threads I6 engaging internalthreadsl I1 in the end of said chamber.

The inner end of the chamber I2 intersects a vertical passage I8preferably formed from the top of the pump and Provided with an enlargedportion I9 adjacent the end of the chamber I2 to provide a shoulder 20forming a seat for a valve 2 I. The upper end of the enlarged portion ofthe passage is preferably closed by a plug 22 having threaded engagementwith internal threads 23 in said passage. The passage I8 extends throughthe pump body and is provided with threads 24 at the bottom of said bodyto receive a pipe or the like 25 having connections with a source ofliquid supply (not shown). Adjacent the end of the chamber I2 which isclosed by the plug I5 and formed from the top of the pump body is apassage 26 terminating short of the chamber I2 and connected therewithby an opening` 21 of reduced size to form a shoulder and valve seat 28for a valve 29, the upper end of said passage 26 being threaded as at 30to receive the threaded end of a pipe 3I preferably connected toasuitable reservoir or circulatory system requiring a liquid supply. .l

The piston 4 is preferably of a. differential type having an upwardlyprojecting concentric auxiliary piston 32 of such length that as thepiston nears the upper limit of its stroke, said auxiliary piston32 willenter a bore 33 extending upwardly in the top 8 of the pump body andterminating adjacent the bottom 33 thereof, the upper end of said bore36 being closed by a suitable plug 31 threaded therein. The lower end ofthe bore 36 intersects a lateral bore 38 drilled through the side I4 ofthe body and having communica.- tion with a chamber 40, the outer end ofsaid bore 38 being closed by a plug 39 threaded therein. It will beunderstood that the passage I8 is offset relative to the passages 34, 36and 38 so that the respective machining operations may be performed andthe proper passages intersect to provide flow through the body as willbe later described.

The chamber 48 is located intermediate the bore 2 and the intersectionbetween the bores 38 and 36 and is preferably formed by a, hole drilledfrom the bottom 3 of the pump and of suitable size to receive a valve 4|adapted to seat on the edges of the passage 38 formed by the chamber 40,said edges forming a valve seat 42 located at the upper end of thechamber 40. The valve is preferably provided with a spring or the like43 for normally holding said valve in closed position relative to thepassage 38. The chamber 40 is provided with a plug 43 threaded thereinto close the opening at the bottom of the pump body. The chamber 40communicates with the bore 2 through a passage 44 in the body I and aport 44' in the side wall of the plug 5. Adjacent the lower end of thepiston 4 at the end of its upward travel is a passage 45 preferablydrilled from the side I4 of the pump body through the passage I8 andinto the bore 2 to provide an exhaust port communicating the bore 2 withthe passage I8, the outer end of the passage 45 being closed by a.suitable plug 46.

In order to provide means for expediting the movement of the piston 4downwardly in the bore 2 a spring 41 is provided in the upper end of thebore 2, said spring having one end engaging the top of the piston 4 andthe other the shoulder I I formed by the end of the bore 2 and thepassage I0.

The plug forms a heating surface and heat is applied thereto by a flamefrom a suitable burner 49 such as a gas, oil or kerosene burner having asuitable source of supply of fuel connected thereto by a duct 50 undercontrol of a suitable valve or control 5| The operation of a pumpingapparatus constructed as described is as follows:

Assuming that the pipe 25 is connected to a suitable source of liquid,the pipe 3| with a suitable reservoir or circulatory system requiring aliquid supply and the line 50 with a fuel supply, a small quantity ofliquid is placed in the cylinder on the plug 5 and the valve or suitablecontrol 5I operated to provide a name 48 for applying heat to the plug 5to vaporize the liquid in the bore 2, it being understood that the pumpmay be primed by liquid to be pumped by removal of any of the plugs, butpreferably the plugs I5 The piston 4 is normally at the bottom of thebore 2 and resting on the side walls of the plug 5 which forms a stopfor the piston due to the resilient force of the spring 41 and thepassage 45 closed thereby. The heat from the flame 48 will vaporize theliquid in the plug 5 at the lower end of the bore forming a vaporpressure in said bore to force the piston 4 upwardly therein against thepressure of the spring 41. Upward movement of the piston 4 forces theliquid in the bore above the piston through the passage I8,

chamber I2, and passage 21, lifting the valve 28 to discharge saidliquid through the pipe 8|. The bore 33 is open for the majority of theupward stroke of the piston 4 so that liquid will fill the bore 33passages 84, 36 and 38. However, the valve 4| maintains the passage 38closed due to the pressure'of the spring 48 andthe vapor pressure in thebore 2.

As the piston 4 approaches the upper end of its stroke, the end of theauxiliary piston 32 enters the bore 33 to apply additional hydraulicpressure therein and the passages 34, 36 and 38 to overcome the pressureof the spring 43 and the vapor pressure in the bore 2 to discharge ametered quantity of fresh liquid supply to the lower end of the bore 2.As the auxiliary piston I2 enters the bore 33, the lower end of thepiston 4 opens the passage 45 to permit exhaust of the vapor pressure inthe bore 2 through said passage 45 into the passage I8 to reduce thepressure in said bore 2. The liquid supply entering the bore 2 from thepassage 38 further reduces pressure in the bore 2 due to the lowertemperature of said liquid supply to effect condensation of some of thevapor in said bore, thereby reducing the pressure in the bore 2 belowthe piston 4 to cause the piston 4 to move downwardly in said boreclosing the passage 45. The pressure of the spring 41 forces the pistonon downwardly in the chamber to provide a suction in the upper end ofthe bore 2 and the chamber I2 which opens the valve 2| and draws aliquid supply through the pipe 25 and passage I8 into the upper end ofthe bore 2. As the piston 4 moves downwardly on its return stroke, theflame 48 vaporzes additional liquid to again provide pressure in thelower end of the bore 2 to effect upward movement of the piston 4 topump liquid from the chamber I2 through the discharge valve 28, pipe 3|to the reservoir or circulatory system, and also provides additionalliquid supply to the lower end of the bore 2 to provide a continuedoperation of the apparatus.

Due to the small quantity of liquid supplied to the bore Lover the plug5, the lower end of the bore 2 acts as a flash type boiler providing afast action to the apparatus for effecting reciprocation of the pumppiston 4 and the vapor pressure in the bore 2 is quickly reduced byexhaust of the pressure through the passage 45 and the reduction ofpressure due to the supply of cold liquid through the passage 38. 'I'hevapor being discharged through the passage 45 is condensed by the liquidin the passage I8 thereby maintaining a low pressure in said passage 45at all times. Control of the flame 48 by means of the valve or control5| controls the rapidity of the vaporzation of the liquid in the lowerend of the bore 2` thereby controlling the speed of the upward movementof the piston 4, the amount of fresh liquid supplied to the bore 2 beingautomatically controlled as a slower moving piston acting against theresistance of the spring 41 will reduce the amount of opening of portl45, entry of the auxiliary piston 32 into the bore 33 thereby reducingthe amount of fresh liquid supply to the' `either the intake valve 2| ordischarge valve 29 may be eliminated.

In the form of the invention shown in Fig. 2 the vapor exhaust passage52 is arranged at an angle relative to the bore 2 and passage I8 so thevapor pressure being exhausted from the bore 2 at the upper end ofthepiston stroke will be directed substantially in the direction of ow ofthe liquid through the passaage I8 thereby providing a jet action toincrease or aid in the flow of liquid through the passage I8. With thisarrangement the pumping apparatus operates substantially in the samemanner as described in the preferred forms except for the advantagesobtained due to the jet action of the exhaust vapor in increasing the'emciency of the apparatus.

In the form of the invention shown in Fig. 3 the pump body 53 isprovided with a cylinder 54 closed by a plug 55; a piston 58 beingreciprocable in said cylinder. Said body also includes an intake passage51 and discharge, passage 58 for ow of liquidto andfrom the. cylinderhead chamber 59, said passages being provided with valves 60 and 6IVrespectively substantially as in the form shown in Fig. 1.

Threaded into thebody 53 and extending into the head chamber over thecylinder 54 is a guide 62 having a bore 63 adapted toreceive-a'pl'ungerl The plunger is providedy with al ring-61 aroundv itsupper end to provide a stop for limiting its downward A movement. Theportion of the plunger extending through thebore 63 is provided with agroove 58 to provide apassage for liquid into the chamber 66, saidgroove. terminating slightly below the guide so that a small amount ofmovement of the plunger closes the lower end of said groove andcontinued upward movement of the plunger forces liquid from the chamber56 through a valve 69 into a coil y1I! which serves as a boiler.

The coil is heated by a suitable burner 1| and the heat of the flametherefrom concentrated around the coil by ahcusng 12. The lower end ofthe coil is connected with the bottom of the plug 55 so that steam orvapor pressure generated in the coil is delivered to the cylinder toeffect reciprocation of the piston in substantially the same-manner asin theform shown in Fig. 1. Resistance tothe upward movement of thepiston is provided by aispring 13 and the vapor pres sure in .thecylinder is vexhausted through a passage 14 connected with theintake 51.The plunger 54 maybe located any place above the piston 56 and isnormally held in the lower position by a spring'15 sleeved over saidplunger and having one end bearing on the `guide 62 fand the otherendonthehe'adBS. .l -1

It is apparent, therefore,l that an economical and eflicien't thermalpump of simple construction and operation is provided by thepresentinvention.

What I claim and desire to secure by Letters Patent is:

l. In a pumping apparatus of the character described, a pump body havinga chamber therein, a, piston reciprocable in said chamber, inlet andoutlet connections in one end ofthe chamber for movement of liquid toand from said chamber in response to reciprocation of said piston, meansfor applying vapor pressure to the other end of the chamber foreffecting movement of the pisment of said piston, and means actuated byreciprocation of said piston for metering liquid to be vaporized to formthe vapor pressure in' said chamber for causing the reciprocation to becontinuous. y

2. In a pumping apparatus of the character described, a pump body havinga chamber therein, a piston reciprocable in the chamber, meansconnecting one end of the chamber with a source of liquid supply, aliquid outlet connected with'said end of the chamber, means operativeresponsive to reciprocation of the piston in the chamber for deliveringa quantity of liquid to the other end of the chamber, means for applyingheat to said other end of the chamber for vaporizing the liquid therein,applying vapor pressure to the piston for moving same toward the firstnamed end of the chamber to force the liquid therein through the outletconnection, means for controlling the vapor pressure in said chamber foreiecting reciprocation of the piston therein, and means actuated byreciprocation of said'pistonfor metering liquid to lbe vaporizedto formthe vapor pressure in said chamber for causingthe reciprocation tobefcontinuous.

in, a piston reciprocable in said chamber, zinlet and outlet connectionsin one end of the chamber for movement of liquid-to and from vsaidchamber in response to reciprocation of4 said piston, means for applyingvapor pressureV to the other endpf the chamber for effecting movement ofthev piston in one direction, means for applying heat-to said other endof the chamber, means controlled by said movement of the piston forreducing vapor pressure in the chamber and reverse movement of saidpiston, an exhaust line extending atan angle communicating with saidchamber and controlled by said movement of the piston for exhausting thevapor pressure in the chamber, and resilient means in the chamber forresisting action of the Vapor pressure on the piston. c 4

4. In a pumping apparatus of the character described, a pump body havinga chamber therein, a piston reciprocable in said chamber, inlet andoutlet connections in one end oi the chamber for movement of liquid toand from said chamber in response to reciprocation of said piston, meansoperative in response to reciprocation of said piston for deliveringliquid to the other end of said chamber, means for vaporizing the liquidin said other end of the chamber for applying vapor pressure to thepiston for eiectingmovement thereof in one direction,an exhaust lineextending to an angle communicating with said chamber and controlled Abysaid movement of the piston for exhausting the Vapor pressure in thechamber, and spring means in the chamber for effecting reverse movementof the piston'whenfthe vapor pressure is exhausted therefrom.

5. In a pumping apparatus of the character described, a pump body havinga chamber therein, a piston reciprocable in said chamber, meansconnecting one end of the chamber lwith the source of liquid supply, aliquid outlet connected with said end of the chamber, meansoperativeresponsive. to reciprocationof the piston in the chamber for deliveringaquantty of l'quid to the other end of the chamber, means for applyingheat to said other end of the chamber for vaporizing the liquid thereinfor applying vapor pressure to thepiston for moving same toward thefirst named end of the chamber to force the liquid 3. In a pumpingapparatus -of the character described, a pump body havinga'chamber-there- Kflcontrolled means connecting one end of the chamberwith a source of liquid supply, valve controlled outlet connected withsaid end of the chamber, a relatively small amount of liquid in theother end of the chamber, means for applying heat to said other end ofthe chamber for vaporizing the liquid therein for applying vaporpressure to the piston for moving same toward the first named end of thechamber to force the liquid therein through the outlet connection, andan auxiliary piston actuated by the first named piston and extendingtoward the first named end of said chamber, said pump body having a boretherein communicating with the chamber, said auxiliary piston beingadapted to enter said bore as the iirst named piston approaches the endof its movement toward the rst named end of the chamber to force aquantityy of liquid into said bore, said pump body having a valvecontrolled passage therein communicating the bore with the second namedend 0f the chamber whereby liquid forced into the bore is delivered tosaid chamber to replenish the supply of liquid therein.

7. In a pumping apparatus of the character described, a pump body havinga chamber therein, a piston reciprocable in said chamber, valvecontrolled means connecting one end of the chamber with a source ofliquid supply, valve controlled outlet connected with said end of thechamber, a relatively small amount of liquid in the other end ofthechamber, means for app-1ying heat to said other end of the chamber forvaporzing the liquid therein for applying vapor pressure to the pistonfor moving same toward the rst named end of the chamber to force theliquid therein through the outlet connection, and an auxiliary pistonactuated by the first named piston and extending toward the first namedend of said chamber, said pump body having a bore therein communicatingWith the chamber, said auxiliary piston being adapted to enter said boreas the first named piston approaches the end of its movement toward therst named end of the chamber to force a quantity of liquid into saidbore, said pump body having a valve controlled passage thereincommunicating the bore with the second named end 0f the chamber wherebyliquid forced into the bore is delivered to said chamber to replenishthe supply of liquid therein, the liquid delivered by the passageeiecting a reduction in temperature and condensation of the vapor in thechamber to reduce the pressures therein.

8. In a pumping apparatus of the character described, a pump body havinga chamber therein, a piston reciprocable in said chamber, valvecontrolled means connecting one end of the chamber with a source ofliquid supply, valve controlled outlet connected with said end of thechamber, a, relatively small amount of liquid in the other end of thechamber, means for applying heat to said other end of the chamber forvaporizing the liquid therein for applying vapor pressure to the pistonfor moving same toward the iirst named end of the chamber to force theliquid therein through the outlet connection, and an auxiliary pistonactuated by the rst named piston and extending toward the iirst namedend of said chamber, said pump body having a bore therein communicatingwith the chamber, said auxiliary piston being adapted to enter said boreas the first named piston approaches the end of its movement toward thefirst named end of the chamber to force a quantity of liquid into saidbore, said pump body having a valve controlled passage thereincommunicating the bore with the second named end of the chamber wherebyliquid forced into the bore is delivered to said chamber to replenishthe supply of liquid therein, the liquid delivered-by the passageeffecting a reduction in temperature and condensation of the vapor inthe chamber to reduce the pressures therein, said pump body having anexhaust passage therein communicating the chamber with the meansconnected with a liquid supply for exhausting and reducing the vaporpressure in the chamber after a predetermined piston travel.

9. In a pumping apparatus of the character described, a pump body havinga chamber therein, a piston reciprocable in said chamber, valvecontrolled means connecting one end of the chamber with a source ofliquid supply, valve controlled outlet connected with said end of thechamber, a relatively small amount of liquid in the other end of thechamber, means for applying heat to said other end of the chamber forvaporizing the liquid therein for applying vapor pressure to the pistonfor moving same toward the first named end of the chamber to force theliquid therein through the outlet connection, an auxiliary pistonactuated by the rst named piston and extending toward the first namedend of said chamber, said pump body having a bore therein communicatingWith the chamber, said auxiliary piston being adapted to enter said boreas the rst named piston approaches the end of its movement toward theiirst named end of the chamber to 'force a quantity of liquid into saidbore, said pump body having a valve controlled passage thereincommunicating the bore with the second named end of the chamber wherebyliquid forced into the bore is delivered to said chamber to replenishthe supply of liquid therein, the liquid delivered by the passageeffecting a reduction in temperature and condensation of the vapor inthe chamber to reduce the pressures therein, said pump having an exhaustpassage therein communicating the chamber with the means connected witha liquid supply for exhausting and reducing the vapor pressure in thechamber after a predetermined piston travel; and resilient means in thechamber for resisting action of the vapor pressures on the piston andeffecting reverse movement of said piston when the vapor pressure in thechamber is reduced.

I 10. In an apparatus of the character described, a body having achamber therein, a second chamber having communication with the firstnamed Chamber, a liquid supply to said body, means for metering aquantity of liquid to said second named chamber, a coil for heating saidliquid and vaporizing said liquid in the second named chamber forapplying vapor pressure to the iirst named chamber, piston means movablein one direction responsive to the vapor pressure in the chamber,exhaust means communicating with said rst named chamber and controlledby movement of said piston means for exhausting the vapor pressure at anangle in the respective chambers for effecting reverse movement of saidpiston means, and means for effecting reverse movement of the pistonafter the vapor pressure acting on the piston is reduced.

1l. In a pumping apparatus of the character described, a pump bodyhaving a chamber therein, a piston reciprocable in the chamber, meansconnecting one end of said chamber with a source of liquid supply, aliquid outlet connected with saidend of the chamber, said liquid outletincluding a guide carrying a plunger having a longitudinal slot thereinand having its lower end engageable with said piston upon upward strokeof the piston, a vapor chamber formingmeans connected with .the otherend of said chamber, means operative responsive to reciprocation of thepiston for delivering a quantity of liquid to said vapor chamber formingmeans, means for applying heat to said chamber forming means forvaporizing the liquid therein and applying the vapor pressure to thepiston for moving same toward the iirst named end of the chamber toforce the liquid therein through the outlet connection, means forcontrolling the vapor pressure in said chamber ior eilectingreciprocation of the piston, and means for effecting reverse movement ofthe piston after the vapor pressure acting on the piston is reduced.

12. In an apparatus of the character described, a body having a chambertherein, means connected with said chamber for forming a vapor pressuretherein, means for exhausting and condensing the vapor pressure in thechamber, a piston reciprocable in said chamber in response to alternateformation, exhaust and condensation of the vapor pressure in the chamberacting on the piston, means actuated by reciprocation of said piston formetering liquid' to be vaporized to form the vapor pressure in saidchamber for causing the reciprocation tobe continuous, and an auxiliarypiston actuated by the rst named pisa valve controlled passage thereincommunicating'the bore with the lower end of the chamber whereby liquidforced into the bore is delivered to said chamber to replenish thesupply of liquid therein.

14. In an apparatus of the character described, a body having a chambertherein, means connected with'sid chamber for forming a vapor pressuretherein, means for exhausting and condensing the vapor pressure in thechamber, a piston reciprocable in vsaid chamber in response to alternateformation, exhaust and condensation of the vapor pressure in the chamberacting on the piston, means actuated by reciprocation of said piston formetering liquid to be vaporized to form the vapor pressure in saidchamber for causingk the reciprocation to be continuous, andan auxiliarypiston actuated by the first named piston and extending toward the upperend of said chamber, said body having a bore therein communicating withthe chamber, said auxiliary piston being adapted to enter said bore asthe first named piston approaches the end of its movement toward theupper end of the chamber to foce a. quantity of liquid into said bore,said body having a valve controlled passage therein communieating thebore with the lower end of the chamber whereby liquid forced into thebore is deliveredto said chamber to replenish the supply of liquidtherein, the liquid delivered by the passage eiecting the reduction intemperature and condensation of the vapor in the 'chamber to reduce thepressures therein.

15. In an apparatus of the character described, a body havnga chambertherein, means connected with said chamber for forming a vapor ton andextending toward' the upper end of said chamber,said body having a boretherein communicating with the chamber, said auxiliary piston beingadapted to enter said bore as the rst named piston approaches the end ofits movement toward the upper end of the chamber to force a quantity ofliquid into said bore.

13. In an apparatus of the character described, a body having a chambertherein, means connected with said chamber for forming a vapor pressuretherein, means for exhausting and condensing the vapor pressure in thechamber, a piston reciprocable in said chamber in response to alternateformation, exhaust and condensation of the vapor pressure in the chamberacting on the piston, means actuated by reciprocation of said piston formetering liquid to be vaporized to form the vapor pressure in saidchamber for causing the reciprocation to be continuous, and an auxiliarypiston actuated by the rst named piston and extending toward the upperend of said chamber, said body having a bore therein communicating withthe chamber, said auxiliary piston being adapted to enter said bore asthe rst named piston approaches the end of its movement toward the upperend of the chamber'to forcea quantity of vliquid into said bore, saidbody having pressure therein, means for exhausting and condensing thevapor pressure in the chamber, a piston reciprocable in said chamber inresponse to alternate formation, exhaust and condensatiom of the vaporpressure in the chamber acting on the piston, means actuated 4.byreciprocation of said piston for metering liquid to be vaporlzed to formthe vapor pressure in said chamber forl causing the reciprocation to becontinuous, and an auxiliary piston actuated by the rst named piston andextending toward the upper end of, said chamber, said body having a boretherein l communicating with the chamber, said auxiliary piston beingadapted to enter said bore as the first named piston approaches the endof its movement toward the upper end of the chamber to force a quantityof liquid into said bore, said body having a valve controlled passagetherein communicating the bore with the lower end of the chamber wherebyliquid forced into the bore is delivered to said chamber to replenishthe supply of liquid therein, the liquid delivered by the. passageeiecting the reduction in temperature and condensation of the vapor inthe chamber to reduce the pressures therein, saidl body having anexhaust passage therein communicating the chamber with the meansconnected with a liquid l supply for exhausting and reducingvthe'vaporpressure inthe chamber lafter a predetermined piston travel. g

EDGAR M. LIEBERMAN.

